Truss-ladder construction



R. S. BOLGER TRUSS LADDER CONSTRUCTION Nov. 12, 1929.

Filed March 6, 1928 r so Patented Nov. 12, .1929

" NITED STATES PATENT OFFICE ROBERT s.

BOLGER, 0F JAMAICA, NEW YORK/ASSIGNOB TO INTERNATIONAL MOTOR COMPANY, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE' TRUSS-LADDER Application filed March 6,

This invention relates to ladder constructions, wherein the rungs are held in blocks secured by longitudinal truss sections. In ladders of this type made of wood it is found that the blocks of wood in which the rungs are mounted have a tendency to split and also that the rungs become loose and revolve when grasped.

This invention has for an object the provision of a construction of the above character wherein the rungs are secured against rotation between the truss members in a manner such that the means for securing the truss members together exerts a normal clamping action upon the rungs to secure them between suitable blocks on the trusses, and for another object, the provision of means whereby the blocks of wood are engaged in such manner that the usual tendency to split is considerably lessened. In order that these objects may be accomplished effectively, the ends of the rungs are flattened and formed sui'liciently wide to separate the sections or the clamping blocks. l/Vhen the securing bolts of the ladder are tightened, these parts have sufficient flexibility to clamp the rungs securely in place in spite of moderate changes in the thickness of the ends.

Other objects will appear as the description proceeds and reference will now be had to the accompanying drawings, wherein:

Figure 1 is a side elevation of a portion of the ladder.

F igure2 is a front elevation of the ladder.

Figure 3 is a side elevation showing the manner of mounting the rungs in the blocks between the trusses.

Figure 4 is a vertical section taken along the line l4; of Figure 3, looking in the direction of the arrows.

Figure 5 is a View in section taken on line 55 of Figure 1 and looking in the direction of the arrows.

In the drawings, a and b represent the upper and lower longitudinal truss members respectively. 0 and 0 represent companion blocks of wood or other suitable material, clamping the flattened ends cl of the rungs (5. The usual blocks for mounting the rungs in existing ladder constructions are supplanted the sections being formed with opposed faces 0 and 0 and recesses c and c which receive the flattened ends of the rungs d. Passing .7

through the upper and lower truss members and companion blocks, and spaced upon ether side of the ends of the rungs, are bolts e which secure the elements together and exert a clamping action upon the ends of the rungs.

In order that the rungs may be clamped securely in place,the thickness of the fiattened ends d, is made greater, in a plane transverse tothat of the ladder, than the total depth of the two recesses, thus separating the opposed faces a and 0* of the blocks and causing the clampingaction of the bolts to be exerted directly upon the flattened ends of the rungs through the blocks. The space between the blocks 0 and 0 is made sufiiciently great at the center to enable the blocks to contact at the outer edges of the faces.

It will be seen that if any tendency of the ends of the rungs to becomeloose appears, the parts will have sufficient elasticity to clamp the ends securely in spiteof changes in size, thus not requiring continual tightening of the bolts. The bolts 0 may be tightened I from time to time, as a safety precaution, and the parts maintained securely fastened together in this manner. It is impossible for the rungs to rotate since the means which secures the parts of the ladder as a unit serves also to clamp each individual rung in po-.

sition. The flattened faces cZ additionally serve to prevent any misalignment of the blocks 0 and 0 At predetermined intervals rungs d are be the ground end as both sides of the rungs present the same kind of tread.

On the under sides of the lower truss members 7), metal tension members 7' are provided. These are secured under the bolt heads 6 and serve to strengthen the ladder very materially.

The truss ladder construction described above has been found to be highly serviceable. It provides a structure in which every element is vital to the proper functioning of the others, and, as a result, the co action'between the component parts is complete. Various modifications indesign and arrangement of parts may be made to suit the requirements of individual needs, and no limitation is to be imposed upon the invention, save as defined in the appended claims.

Iclaim as my invention:

'1. A ladder construction of the character described comprising spaced truss members, rungs, companion blocks between the truss members, means to secure the rungs in the blocks, and means to secure the blocks between the truss members.

2. A ladder construction or" the character described comprising spaced truss members, rungs, companion blocks between the truss members, means to secure the rungs between the blocks, and means to secure the blocks between the truss members.

3. A ladder construction of the character described comprising spaced truss members, rungs, companion blocks between the truss members, means to mount the rungs between the blocks, and meansto clamp the rungs between the blocks. V t. A ladder construction of the character described comprising truss members, rungs having flattened surfaces at their ends, companion blocks between the truss members, meansto mount the rungs between the blocks, and means to clamp the flattened ends of the rungs between the blocks.

5. A construction of the character described comprising truss members, rungs having flattened surfaces at their ends, companion blocks between the truss members, spaced recesses in the blocks to receive the ends of the rungs, the combined depth ofthe recesses being less than the thickness of the ends of the rungs, and means to secure the truss members and blocks together to clamp the rungs in position. 7

6. A ladder construction of the character described comprising upper and lower longitudinal truss members at either side of the ladder, means to secure rungsbetween the truss members, and metallic tension members secured to the lower truss members.

7. ladder comprising side members, a plurality of rungs mounted between the side members, shoulders on the rungs to engage the side members'to space the members properl'y, and means passing through certain of the rungs to secure the side members against the shoulders, the lengths of the rungs between shoulders and adjacent ends being less than the thickness of the side members.

8. A ladder construction of the character described comprising 5 aced truss members, rungs, companion bloc s between the truss members, said blocks being formed with depressions in which the rungs seat, the combined depth of the depressions being less than the corresponding dimensions of the rungs, means to secure the rungs in the depressions, and means to secure the blocks between the truss members.

This specification signed this 2nd day of March, A. D. 1-928.

ROBERT S. BOLGER. 

